Does pain score in response to a standardized subcutaneous local anesthetic injection predict epidural steroid injection outcomes in patients with lumbosacral radiculopathy? A prospective correlational study

Objective: Epidural steroid injections (ESI) are the most commonly performed pain procedures. Despite numerous studies, controversy continues to surround their effectiveness. The purpose of this study is to determine whether a standard, clinical local anesthetic injection can predict outcomes for ESI. Study Design: In this multicenter study, 103 patients received two ESI 2 weeks apart. Prior to their first injection, subjects rated the pain intensity of a standardized subcutaneous (SQ) injection of lidocaine prior to the full dose. Numerical rating scale pain scores were correlated with leg and back pain relief, and functional improvement, through 3-month follow-up. Outcome Measures: A composite successful outcome was predetermined to be a ≥2-point decrease in leg pain score, coupled with a positive global perceived effect. Results: A small but significant relationship was found between SQ pain score and reduction in leg (r=-0.21, 95% CI -0.38 to -0.04; P=0.03) and back pain (r=-0.22, 95% CI -0.36 to -0.07; P=0.03). Subjects with a positive outcome at 1 month had a mean SQ pain score of 2.5 (SD 1.9) vs 4.1 (SD 2.7) in those with a negative outcome (P=0.04). Subjects with SQ pain scores <4/10 had lower leg and back pain scores than those with pain scores ≥4 at 1-month (mean 3.2, SD 2.6 vs 5.1, SD 2.7 for leg, P<0.01; mean 3.7, SD 2.6 vs 5.0, SD 3.0 for back, P=0.02) and 3-month (mean 3.8, SD 2.7 vs 5.2, SD 3.1 for leg, P=0.01; mean 4.0, SD 2.6 vs 4.9, SD 3.1 for back; P=0.14) follow-up. Conclusions: The results of this study found a weak positive correlation between SQ pain scores and treatment results. Further research should consider whether pain perception in conjunction with other variables might prove to be a reliable predictor for ESI and other procedural outcomes.